LABORATOIRE NATIONAL CANADIEN POUR LA RECHERCHE EN PHYSIQUE NUCLÉAIRE ET EN PHYSIQUE DES PARTICULES

Propriété d’un consortium d’universités canadiennes, géré en co-entreprise à partir d’une contribution administrée par le Conseil national de recherches Canada

In-Trap Spectroscopy at TITAN for

NME Calculations

Thomas Brunner for the TITAN collaboration

Single-State Dominance hypothesis

Transition via lowest 1+ state in

intermediate nucleus accounts for

entire M2ν

D. Fang et al., Phys. Rev. C 81(2010)037303

Figure from S.K.L. Sjue et al., Phys. Rev. C 78(2008)064317

ββ−−

0+

0+

0+

Tc

β−

Ru100

2

QEC

=168 keV

Qβ

=3202 keV

ECMo100

1001+

+

E x= 1130 keV

E x= 540 keV

BR EC=0.0026%

∑+−

∝

++

m im

i

sgmm

f

sg

QEE

OOM

2

0ˆ11ˆ0 ....2

ββ

ν

EC-BR Motivation

• Experimental data required to test theoretical models describing ββ

• (Only) 2νββ accessible experimentally

� testing ground for nuclear models

• ECBRs provide information about g.s. properties of the nucl. wave

function connected to ββ decay (2νββ, 0νββ)

2

J.H. Thies et. al. Phys. Rev. C 86:044309 2012

Physics case 100MoAlmost the entire low energy GT

strength is located in one single

state only! (i.e. the g.s.)

• (3He,t) measurement by Ejiri et al. in 1998 with ∆E = 300 keV

� B(GT)(g.s.) = 0.33(4)

• Recent (3He,t) measurement by Thies et. al. with ∆E = 29 keV

� B(GT)(g.s) = 0.35(1)

• In conflict with BR(EC) measurement from 100Tc by Sjue et.al.

� B(GT) = 0.60(9)

0 1 2 3 4 4 6 8 10 12 14 16 18 20 22 24 26 28 30

10

-3 y

ield

/(5

ke

V m

sr)

Ex [MeV]

100Mo(3He,t)100Tc

0

1

2

3

4

6

5

0.2

22

(2

−)

1.3

39 (

1+)

1.4

16 (

1+)

0.3

54 (

1+)

0.6

89

(2

−)

0.8

38 (

1+)

g.s

. (1

+)

E = 420 MeV

−E = 33 keV

0.0° < − lab < 0.5°

IAS

GTR

SDR

0

4

8

12

18

20

10

-3 y

ield

/(5

ke

V m

sr)

10.8Ex [MeV]

IAS

11.3

1.0° < − lab < 1.5°

2.0° < − lab < 2.5°

11.0

85 M

eV

(0

+)

12N

g.s

.

M tot

2ν ≈MECMβ−

1

2Qββ (0g.s.

+( f ))+Eg.s.(1+ )−E0

For SSD the NME simplifies to:

3

Challenges in EC BR measurementsChallenges

• Difficult measurement due to a weak EC branch and difficult x-ray signatures

• High background due to dominating beta decay and possible bremsstrahlung

• Isobaric contamination

New approach using a Penning trap (Frekers et al., Can. J. Phys 85(2007)57)

ββ−−

0+

0+

0+

Tc

β−

Ru100

2

QEC

=168 keV

Qβ=3202 keV

ECMo100

1001+

+

E x= 1130 keV

E x= 540 keV

BR EC=0.0026%

5/13/2016 Thomas Brunner 4

Basic concept of TITAN-EC

Injection of ions

Storage of ions

Observation of decays

Ejection of ions

The trap is kept open to

empty completely

Empty trap

Background measurement

V

z

• Ions stored in EBIT

• Backing free environment

• Spatial separation of β- and

photon detection

• Potential to clean ion sample

5/13/2016 Thomas Brunner 5

B-field up to 5.5T Measurement cycle

TITAN-EC detector configuration

5/13/2016

Advantages of the TITAN-EC program:

• Pure and intense ion beams from ISAC

• No isobaric contamination of the sample

• No X-ray absorption

• Open trap access for 7 X-ray detectors

• Shielded detectors

• Spatial separation of X-rays and β− by B-field

� Potential to measure weak ECBRs (10-4)

Acceptance ~2.1%

Leach et al., NIMA 780(2015)91

Thomas Brunner 6

ISAC

TITAN

5/13/2016 Thomas Brunner 7

500 MeV proton beam

Up to ~100 µA

• Production of rare ion

beams

• Irradiation of thick

production target with

proton beam

RFQ LinearPaul Trap

ISACBeam

Beam To Next Experiment

Spectroscopy Penning trap / EBIT

MPET precision Penning trap

N

S

W

E

Transfer Beam Line

1 meter

νc

=1

2π

q

m⋅B

TRIUMF’s Ion Trap for Atomic and Nuclear science

Radiofrequency Quadrupole

- RFQ

• Cooler and buncher

Electron Beam Ion

Trap – EBIT

•Charge breeder

•Spectroscopy ion

trap

Measurement Penning Trap

(MPET)

• High-precision mass

measurements

TITAN

5/13/2016 Thomas Brunner 8

Commissioning experiments – 124Cs

462.57+

1+

124Cs

0+

124Xe

30.9(4) s

6.3(2) s

QEC

=5917

5− 397.7

4− 301.1

3+ 242.93+ 211.62+ 189.0

96.6

89.553.9

~50

124Sn

124In

0+

1+

8− 3.7(2) s

3.12(9) s

2324.97−

2204.55− 120.3

2101.64+ 102.9

1131.62+

2+

354.1

Qβ=7360

58.249

50 54

55

0

5000

10000

15000

20000

25000

20 40 60 80 100 120 140

Counts / 100 eV

Energy [keV]

53.9 keV

58.2 keV

89.5 keV

96.6 keV

102.9 keV

120.3 keV

124Cs 7

+ 124In 8

-

Sn, Cs, Xe

X-rays

Trapping time (20s)

Background (4*5s) • 124Cs High ECBR ~7%, T1/2=30.9 s

• Beam composition: 124Cs g.s., 124mCs, 124mIn

• X-rays from 3 isobars: Sn, Xe, Cs

• 6 Si(Li)s, 1 HPGe

• Used electron beam for ion trapping

• Charge bred Cs to q=27+ (average)

� better ion confinement

� Factor of 20 511 keV suppression

IT

IT

ECA. Lennarz et. al., Phys. Rev. Lett. 113, 082502 (2014)

Slide courtesy of

A. Lennarz

5/13/2016 Thomas Brunner 9

Time structure1.6

1.4

1.2

1.0

0.8

0.4

0.2

Counts

/ 1

00 e

V

0.6

0

x104 a) [0-5s]

Energy [keV]

20 25 30 35 40 25 30 35 40 20 25 30 35 40 20 25 30 35 40

b) [5-10s] c) [10-15s] d) [15-20s]

6.0

5.0

4.0

3.0

1.0

2.0

7.0

0

20

x103

2.0

1.5

1.0

0.5

2.5

0

x103

1.2

1.0

0.8

0.6

1.4

0

0.4

0.2

x103

Xe K

β

Xe K

α

Cs K

β

Cs K

α

Sn K

βSn K

α

Sn K

α

Xe K

αC

s K

α

Sn K

β

Xe K

β

Cs K

β

Sn K

α

Xe K

β

Cs K

β

Xe K

βC

s K

β

Xe K

α

Sn K

β

Cs K

α

Sn K

α Xe K

α

Cs K

α

Sn K

β

• Time-stamped events

� Identify contaminants

• Reduction of 124mIn (3.7s) and 124mCs (6.3s)

• Xe X-rays dominant towards longer Ttrap

• T1/2 determination possible

Slide courtesy of

A. Lennarz

5/13/2016 Thomas Brunner 10

Half-lives

124mIn 124Sn 124mCs 124Cs 124Cs 124Xe

Counts

/s

Decay time [s]

2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 200103

104

105

103

104

2

3

4

5

x103

124Sn X-ray counts 124Cs X-ray counts 124Xe X-ray counts

T1/2

=3.68(3) s T1/2

=6.41(7) s T1/2

=31(3) s

• Measured T1/2 confirm lit. values

• Accuracy increased for 124mIn & 124mCs

� Efficient trapping for order of minutes

� Understand background

• Calculate Nions in the trap via

activity at tdecay=0s

� Information about transport eff.

� Calculate beam composition:124mCs 3%, 124Cs 65%, and 124mIn 32%

T1/2=3.68(3)s T1/2=6.41(7)s T1/2=31(3)s

Slide courtesy of

A. Lennarz

Atomic structure effects in highly-charged ionsX

-ray e

ne

rgy [

keV

]

35.4

35.3

35.2

35.1

35.0

34.9

34.8

31.0

30.9

30.8

30.7

30.6

Cs ion charge state

-5 0 5 10 15 20 30 3525 40

Kα1

Kα2

Kβ1

Kβ3• Charge breeding � atomic structure is altered

• Electron correlation, relativistic & quantum

electrodynamical effects

• Electronic-binding energies get larger with

increased charge state

• � Atomic spectrum varies with the electronic

configuration

• � Ionization-energy shift

• Multiconfigurational Dirac-Fock code FAC

(flexible atomic code)

� Calculate atomic collisional & radiative processes

Η = HD (i) +1

riji≤ j

N

∑i=1

N

∑

single electron Dirac operator for the ith electron in

the potential field of the nucleus

Non-relativistic

Coulomb

interaction operator

Slide courtesy of

A. Lennarz

X-ray energy shifts and intensity ratios

• Observed K-shell X-ray energy shift

• Consistent with FAC calculation

Species Shift [eV] FAC

Xe 96(37) 92

Cs 120(34) 111

Sn 139(34) 143

In low-energy X-ray:

Accuracy 50 eV

≈1.1 keV spectral resolution

5/13/2016 Thomas Brunner 13

X-ray intensity ratios

• Stripping N-shell

� Kβ2 transition is non-existent

• Expected is an increased Kα/Kβ ratio

• BUT: Measured Kα/Kβ X-ray intensity

ratio is consistent with neutral atom

• Neutral atoms: Auger effect competes

with X-ray emission & limits emission

probability of Kβ X-rays.

• Highly charged ions: Fewer electrons,

Auger effect reduced

• Emission probabilities change

� higher Kβ13 intensity.

Species Kα/Kβ exp.

Xe 4.95(66)

Cs 4.48(37)

Sn 5.01(49)

0.17

0.18

0.19

0.2

0.21

0.22

0.23

0.24

0 5 10 15 20 25 30 35 40

Charge stat e

124Cs Kβ / Kα ratio without Kβ2 (FAC)

Measured ratio

Xe

Kα/Kβ neut. Kα/Kβ no Kβ2

4.69(11) 5.63(13)

4.63(10) 5.58(13)

4.91(11) 5.80(13)

Slide courtesy of

A. Lennarz

5/13/2016 Thomas Brunner 14

116In – first attempt of a physics

measurement

• Intermediate nucleus in ββ decay of 116Cd

• Goal: Observe Cd EC X-rays

• Problems:

� Low g.s. yield (~104 pps), high isomeric

yields (5+:106 pps,8-:105 pps)

� Weak EC branch

• Observed In and Sn X-rays (time

structure)

162 keV

Wrede et al. Phys. Rev. C – Nucl. Phys. 87(3),  2013

5/13/2016 Thomas Brunner 15

Slide courtesy of

A. Lennarz

116In – Multiple ion-bunch injection

• Maximize statistics in limited time

• Overcome RFQ space-charge

limit ~106 ions

• Multiple ion bunch stacking

• First ever MI with RIBs

• Tested up to 3000 injections in

15s

• Stored ~109 ions in the trap

Courtesy of R. Klawitter

a: injection of A+

ions

b: trapping during

charge breading

c: potential a seen

by A>1+

Perform measurements even at lower ISAC

beam rates!5/13/2016 16

Summary

Candidates for TITAN-EC

ββ-nucleus Interm.

nucleus

transition T1/2 Kα-energy

(keV)

100Mo 100Tc (EC) 1+�0+ 15.8 s 17.5

110Pd 110Ag (EC) 1+�0+ 24.6 s 21.2

114Cd 114In (EC) 1+�0+ 71.9 s 25.3

116Cd 116In (EC) 1+�0+ 14.1 s 25.3

82Se 82mBr (EC) 2-�0+ 6.1 min 11.2

128Te 128I (EC) 1+�0+ 25.0 min 27.5

76Ge 76As (EC) 2-�0+ 26.2 h 9.9

• TITAN-EC is a powerful technique to measure weak EC branches

• Successful commissioning of technique with 124Cs

• Technique suited for atomic spectroscopy measurements

• Beam purification from isobaric contamination coming soon (MR-TOF)

• 116In planned for fall 2016 (TRIUMF proposal S1622)

SSD

SSD

Input from theorists required:

• Prioritize isotopes in list

• Suggest different isotopes

• Suggest different

experiment

17

Acknowledgements – Thanks to the TITAN group!

M. Alanssari, C. Andreoiu, J. Bale, B. Barquest, T. Brunner, U. Chowdhury, J. Dilling, J. Even, A.

Finlay, D. Frekers, A. T. Gallant, M. Good, A. Großheim, R. Klawitter, B. Kootte, A. A. Kwiatkowski,

D. Lascar, K. G. Leach, A. Lennarz, E. Leistenschneider, T. D. Macdonald, B. Schultz, R. Schupp

S. Seeraji, M. Simon, D. Short, P and the TITAN collaboration

M. Alanssari, C. Andreoiu, J. Bale, B. Barquest, T. Brunner, U. Chowdhury, J. Dilling, J. Even, A.

Finlay, D. Frekers, A. T. Gallant, M. Good, A. Großheim, R. Klawitter, B. Kootte, A. A. Kwiatkowski,

D. Lascar, K. G. Leach, A. Lennarz, E. Leistenschneider, T. D. Macdonald, B. Schultz, R. Schupp

S. Seeraji, M. Simon, D. Short, P and the TITAN collaboration

U. of Manitoba

McGill U.

Muenster U.

MPI-K

SFU

UBC

Mines

TRIUMF18